Process for treating crude pine tar



. bewithdrawn. However, this method is not effec- Pa'tented July3, 1945 I UNITED STATES PATENT OFF TREATING CRUDE PINE TAR Wiley 0. Smith, Arlington,

. rnoonss Foa ICE Va., assignor to the United States of America, 'as represented by :Claude R. Wickard, Sec and his successors in ofl'ice rotary of Agriculture,

N Drawing. Application October-4, 1944,

Serial No. 557,212

3 Claims. (01. 260407) (Granted under the act of March 3, 1883, as amended April 30, 192.8; 370 0. G. 757) This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described and claimed, if patented, may hie-manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to me of any royalty thereon.

This isa continuation in part of my copending application for patent, Serial No. 400,881, filed .July 2, 1941, nowPatentNo. 2,364,104.

. This invention relates to the treatment of crude pinetars to obtain more desirable products. .It is particularlywell adapted to the treatment of tars made by the kiln process.

n An object of my invention is to remove from pine tar not only the dirt andother solid extra.-

neous matter, but also both free and dissolved water.

Another object is to eliminate the losses which result from the usualdistillation of tar. Still another object is to provide a means of obtaining a purified tar having a desired viscosity and other properties. i

H Pine tars are obtained from the stumps and other resinous wood of the pine and certain other conifers by two general processes. In one process, the resinous woodis carbonized in metalre- :torts.- Tar and lighter volatile. oils which are .driven from the wood by the destructive distillation are condensed by cooling and separatedinto rough fractions. The crudetarmay bedistilled to produce various gradesof tars and tar oils. A dis- .tillation oftar usually results in an appreciable .loss by cracking withthe formation of water and uncondensed gases. Also the pitch which is formed by the distillation is of less value than are tars and tar oils. .Tars made by this process are commonlyreferred. to as .retorttars.

.In the other process, the resinous wood is carbonized by subdued combustion in kilns. Gases and light volatile oils escape, into the air and are lost. The tar which is produced runs through channels in the floor of the. kiln into an outside pit, or receptacle.- Tars produced by this process :commonly are known as kiln tars. Tars made by a similar process in Sweden and other north I European countries are known locally as valley a flth H l r v Kiln tar as it is first produced contains large quantities of pyroligneous acid and. certain solid extraneous matter such as sandyclay, charcoal, etc.. Before packaging, the tar is allowed to stand in order that the heavy solids may settle and the pyroligneous acid may separate from-the tar and in disinfectants, and for a number of other purposes. The desired properties of ajtar willvary according to the use for which it is intended. Tars i may be classed in accordance with specific gravity and viscosity asthin, medium, and heavy; the thin tar having the lowest specific gravity and viscosity. Retort tars can be made to cover'a wide range in viscosities by distillation and coml p u ding.

.stricts its use. The

closely the properties water is formed by The composition and propertiesof kiln tar will vary somewhat depending on the conditions of operation. The maker of kiln tar cannot control ence of dirt and excess moisture in kiln tar re- Navy Department specifies that pine tar shall be a high grade retort tar, free from dirt and foreign matter, other than water, which shall not exceed 2 percent. The water is determined by distilling up to 200 0. Above 200 the cracking of certain constituents of the tar. Thistolerance of 2 percent is to cover dissolved water. 1 a r I have found that tures will dissolveabout 1.6 percent of water or pyroligneous acid. The removal of dissolvedwater from pine tar will reduce its corrosiveness to metal and enhance its value as a paint constitiuent. Crude pine tars consist of ;a mixture of unchanged constituents of r the oleoresin derived from the Wood, and pyrogenated the oleoresin and the wood. The constituents of will almost completely dissolve pine tars, except for thewater and solid extraneous Crude kiln tars which of his products. The preskiln tar at ordinary tempera? products of both matter, while the lighter petroleum distillates fail example, coal tar hydrocarbons, petroleum disto dissolve a substantial portion of the tar, espetillates, etc. Also, the heavy viscous portion of cially at the lower concentrations. crude kiln tar, which is precipitated by the dilu- I have found that spirits of turpentine has a tion with turpentine, has more, desirable properse-lective "solvent 'act'ioi for the constituents of ties-thanthat precipitated by petroleumdistiltar which is difierent from that of the other comlates, and other solvents.

mon solvents and that the turpentine insoluble' fi After the Water, solid extraneous matter and material (other than waterfand solid entrane a the. insolubleportions have been separated from ous matter) has valuable propertisf 'Thi's tur "the "diluted tar';"'the'" added solvent is removed by are that it is 'siibstantia-lly -i treatingwtype is requifed'g the i solvei pentine insoluble material also has ahigher spe- Q. distillation The dissolved water is distilled off cific gravity and a much greaterpviscosity than along 'wi-th"the--solvent. If a low viscosity tar is the original tars so that itsrremovalwfll reduce' desired. he distillation is stopped as soon as the the specific gravity and viscosity of the tar. added solverithats been recovered. If turpentine regulation of the removal of the quantity'of this is used as, a solvent, the distillation may be turpentine insoluble material wnreause'avett ng- 's 'stzirspeaterere all'the added turpentine has been tion in the specific gravity and viscosity ofthe recovered, the higher boiling portion of the turtar.- The addition of the lower boiling eassure-m pentin' remainingin the tar tends to reduce its ents to tar will cause a decrease inthespecific viscosity and specific gravity. l gravity and viscosity of th'tar'fi'Thdi'rfiinutioiif 1 If a e star is desired, the distillation "co"rl'ti'riiied after the added solvent has of the lower boiling constituents increases the Z'Wn'lay be specific gravity andgviscosity of 'tlie tari been-recovereduntilthetemprature has reabhed I Tne-proeess' or eatiii'gfci ud 'kilfr'tai acold as liigfi a200"*'.;.therbyflmbvin'g somof the in'g tomy in'veiiti n consist'sf'in briei,"of"the"relighterandlowerboiling constituentsaof the ?tar, m'oval 'o'flthe freewa ter; 'undissolved'sol'ideicwhich may be "'eollecte-dlseparately. 'These' lower traneous matter-g and a -"desiredportion or the boiliflg constituhts, -whloh wereremoved by the heaviest and most viscous coi'n'porie'rit dfl'the' tar, cdntinueddistill'ation, maybeadde'd to' other tar s which-is followed by'theremovar of the-dissolved to reduce "further" their: viscosity p fi wa'ten' r i 7 gravityw Turpentine a'nd "other higher boiling The word 'fw aiter" 'cove'rs tlie aqueous portion solvents, on renivahfrdm t-he 'diluted ita i i of tar whic'h co n ain'sf 'aiiids pfiiils }-'aridother. tillation, carry over a smaill qiiantitylofilpfiefiol. substari'cesy and generau These pl renols imay loeremoved mfi swashing"lthe pyfdlig'nebfis solventwithaqueous sodimmhydrbkide. Theirscovei'ed "solvent ma'y be 'rep'eatedly fiused without have'a='specific "gravit -L removal of the phenols. i- 1* I l although t us'lially has spe v vThedilutionfand settling 'bfithe crudei tai 'may afiiundI-QB whereas the s'pecific g'ravity-Qof c'rude beca'rri'ed out in a' maririr similai to that whibh kiln tar is around 1.08, w ile that of crude rtort crudepine:"gum-"and axialogousmaterials arei diis 1 luted. andsettled. The diluted-tar afteriiseparatiofi from' the ex- "t "40 traneous matter and irisolulclemartinisifrray zlae distilled 1 to recover the added solventin 1 a "Still such asi's usedte distin crudp 'e 'gumf-oi' lii -any other suitable still. Steam maizbe' mjeeteirduring thefifirst partof 'tlie distillationgbut thef m- 145 "jec'tiorr of water, or -steair'ri-,='must'- discontinued visco' ty orenxae ki diffiell'ce betweent sit matter prevent aa-errec removal 'o'f' the uiide'si willtd'ec'rea'se 'its s'o' that theextrari gravity-atom the'-"' The g'en'e'rahr move the water' fror'n'the tar."

td' some e'xteht on the 'propeities of the tre: '55 ls effected afid' then aiidwed to stana "rent,

tar. As an example, if a heavy tar of the cordage "or for at lea'st tw munge used-for the rdilute'd tar sep rates from the etc. The diluted tar maybe plaed-m-a-still iand heate'u to substantia11yY15o "Cwwhen steam iiiay thinning thebcrude tar to s' ar'ate h' and "sol-id extraneous' matte hould pr "a minimum-of the heavy/ viscous=por t1on r the be injectediandidistillation lby steamrcarrfed on tan]. For most: purposes; "however; a tarfrom -until'fth'ei soIi ent-IrecSGV-erew equals Siib ritlallly .which'isome "of the tuiperltlfleiriSduMe pdrtioh '95%*df the"Sd1Veiiif-'added, fl I'h Stam=-1fije6tibn Anumberofsolvents may be usedfertile-purtar' raised to '170 13 to -drive outz anyrresidual "eater part c'f 'th chloride; chloroform, coal tar hydrocarbons, uble portion bi the wr. I petroleumwdistillates, .and' spirits*ofturperitine. The tar resulting from the above proces While I prefer spirits of turpentineas 'a solverit, tained n' free and/on dissolved water;

because it-is; similar to some naturaTcon'stituehts 4 7.0 unifori ri composition an hacl la; viseosity 'fi- .ofpine:tartandyitwis riot necessary to' completely preaching-i a -Wthim remoyeitfrom the dilutedtar, in order"to obtain wouldE'b cla'ssedira' "heavy a desirable refined tar', I "may, -for the purposes greater 7.

'roportion ofivtui pen o f my; invention,'-zemploy other-"-solvents; having wouldih'ave precipitated a greater-d anti-11y:

before distillatiorr'iswcompleted, in' order to re- Thefollowing eirafmpleiwill srve mum-ate one volume of spirits dfi turpentine tspwgr.

maylbe "discontinuedgand' the temperaiture ofitiie quantities of the various solvents to use for dilution, nor the maximum temperature to which the distillation for removal of added solvent should be carried, in general, dilution of the crude tar with an equal volume of solvent is deemed sufiicient to effect separation of free water, and other extraneous matter. The dilution with larger portions up to two volumes of turpentine and/or petroleum spirits may be made to obtain separation of substantially a maximum portion of the viscou material. For the production of a heavy tar the diluted tar may be distilled until the temperature reaches substantially 200 0.

Having thus described my invention, I claim: 1. A process for treating crude kiln pine tar containing impurities in aqueous solution to procentby volume and a maximum boiling point of not exceeding about 175 C., then agitating the mass, separating the diluted tar from the aqueous solution, then heating the diluted tar to a temperature of about 100 to 170 C. to drive off the solvent and dissolved water, and recovering the residue.

2. A process for treating crude kiln pine tar in. the production of a water-free refined product'comprising diluting the tar with carbon tetrachloride and agitating the mass, then separating the diluted tar from tar at a temperatureof about 100 to 170 C. to

drive oil? the carbon tetrachloride and dissolved in the production of a water-free refined prodv uct comprising diluting the tar with chloroform duce a substantially water-free refined product,

comprising diluting the tar with a solvent to form a solution with the tar having a specific gravity 'diflerent from the aqueous solution, said solvent having a solubility in water of less than 1 perand agitating the mass, then, separating the diluted tar from the waterand other insoluble materials present, then heating the diluted tar at a temperature of about to C. to drive ofi the chloroform and dissolved water, and recovering the residue. t

, WILEY 0. SMITH.

the water and other insoluble materials present, then heating the diluted 

